4 files changed, 46 insertions, 53 deletions

diff --git a/include/linux/sched.h b/include/linux/sched.h
index d35d2b6ddbfb..aefe45d79f53 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -320,7 +320,6 @@ extern signed long schedule_timeout_killable(signed long timeout);
 extern signed long schedule_timeout_uninterruptible(signed long timeout);
 asmlinkage void schedule(void);
 extern void schedule_preempt_disabled(void);
-extern int mutex_spin_on_owner(struct mutex *lock, struct task_struct *owner);
 
 struct nsproxy;
 struct user_namespace;
diff --git a/kernel/mutex.c b/kernel/mutex.c
index 52f23011b6e0..262d7177adad 100644
--- a/kernel/mutex.c
+++ b/kernel/mutex.c
@@ -95,6 +95,52 @@ void __sched mutex_lock(struct mutex *lock)
 EXPORT_SYMBOL(mutex_lock);
 #endif
 
+#ifdef CONFIG_MUTEX_SPIN_ON_OWNER
+/*
+ * Mutex spinning code migrated from kernel/sched/core.c
+ */
+
+static inline bool owner_running(struct mutex *lock, struct task_struct *owner)
+{
+        if (lock->owner != owner)
+                return false;
+
+        /*
+         * Ensure we emit the owner->on_cpu, dereference _after_ checking
+         * lock->owner still matches owner, if that fails, owner might
+         * point to free()d memory, if it still matches, the rcu_read_lock()
+         * ensures the memory stays valid.
+         */
+        barrier();
+
+        return owner->on_cpu;
+}
+
+/*
+ * Look out! "owner" is an entirely speculative pointer
+ * access and not reliable.
+ */
+static noinline
+int mutex_spin_on_owner(struct mutex *lock, struct task_struct *owner)
+{
+        rcu_read_lock();
+        while (owner_running(lock, owner)) {
+                if (need_resched())
+                        break;
+
+                arch_mutex_cpu_relax();
+        }
+        rcu_read_unlock();
+
+        /*
+         * We break out the loop above on need_resched() and when the
+         * owner changed, which is a sign for heavy contention. Return
+         * success only when lock->owner is NULL.
+         */
+        return lock->owner == NULL;
+}
+#endif
+
 static __used noinline void __sched __mutex_unlock_slowpath(atomic_t *lock_count);
 
 /**
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 7f12624a393c..b37a22b99e0e 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -2997,51 +2997,6 @@ void __sched schedule_preempt_disabled(void)
         preempt_disable();
 }
 
-#ifdef CONFIG_MUTEX_SPIN_ON_OWNER
-
-static inline bool owner_running(struct mutex *lock, struct task_struct *owner)
-{
-        if (lock->owner != owner)
-                return false;
-
-        /*
-         * Ensure we emit the owner->on_cpu, dereference _after_ checking
-         * lock->owner still matches owner, if that fails, owner might
-         * point to free()d memory, if it still matches, the rcu_read_lock()
-         * ensures the memory stays valid.
-         */
-        barrier();
-
-        return owner->on_cpu;
-}
-
-/*
- * Look out! "owner" is an entirely speculative pointer
- * access and not reliable.
- */
-int mutex_spin_on_owner(struct mutex *lock, struct task_struct *owner)
-{
-        if (!sched_feat(OWNER_SPIN))
-                return 0;
-
-        rcu_read_lock();
-        while (owner_running(lock, owner)) {
-                if (need_resched())
-                        break;
-
-                arch_mutex_cpu_relax();
-        }
-        rcu_read_unlock();
-
-        /*
-         * We break out the loop above on need_resched() and when the
-         * owner changed, which is a sign for heavy contention. Return
-         * success only when lock->owner is NULL.
-         */
-        return lock->owner == NULL;
-}
-#endif
-
 #ifdef CONFIG_PREEMPT
 /*
  * this is the entry point to schedule() from in-kernel preemption
diff --git a/kernel/sched/features.h b/kernel/sched/features.h
index 1ad1d2b5395f..99399f8e4799 100644
--- a/kernel/sched/features.h
+++ b/kernel/sched/features.h
@@ -46,13 +46,6 @@ SCHED_FEAT(DOUBLE_TICK, false)
 SCHED_FEAT(LB_BIAS, true)
 
 /*
- * Spin-wait on mutex acquisition when the mutex owner is running on
- * another cpu -- assumes that when the owner is running, it will soon
- * release the lock. Decreases scheduling overhead.
- */
-SCHED_FEAT(OWNER_SPIN, true)
-
-/*
  * Decrement CPU power based on time not spent running tasks
  */
 SCHED_FEAT(NONTASK_POWER, true)